1. Field of the Invention
The present invention relates to a bioelectrical impedance measuring apparatus which measures the bioelectrical impedance of a living body, and relates to a bioelectrical impedance measuring apparatus which measures body fat, body water, pulse, blood pressure and such like as well as a bioelectrical impedance of a living body.
2. Prior Art
Some examples of conventional bioelectrical impedance measuring apparatus include a cable-connected electrode type of impedance meter 10, a hand-held electrode type of impedance meter 20, and a foot sole-contacting electrode type of impedance meter 30. As shown in FIG. 1, the cable-connected electrode type of impedance meter 10 has a pair of measurement current supplying electrodes 12a, 12b and a pair of voltage measuring electrodes 13a, 13b connected to its cables 11 (hereinafter, a measurement current supplying electrode is called a xe2x80x9ccurrent electrodexe2x80x9d and a voltage measuring electrode is called a xe2x80x9cvoltage electrodexe2x80x9d in the specification and claims). In measuring bioelectrical impedance, these electrodes are attached on both hands, both feet or one hand and one foot to measure the bioelectrical impedance appearing therebetween. As shown in FIG. 2, the hand-held electrode type of impedance meter 20 has a pair of current electrodes 22a, 22b and a pair of voltage electrodes 23a, 23b placed on its opposite grips 21a, 21b. In measuring bioelectrical impedance, these electrodes are gripped in both hands to measure the bioelectrical impedance appearing therebetween. As shown in FIG. 3, the foot sole-contacting electrode type of impedance meter 30 has a pair of current electrodes 32a, 32b and a pair of voltage electrodes 33a, 33b placed on its platform 31. A user who wants to measure his bioelectrical impedance stands on the platform, thus measuring the bioelectrical impedance appearing between his feet. Thus, all of these apparatuses require that the bioelectrical impedance be measured by applying two pairs of electrodes to two selected body parts, such as both hands, both feet, or one hand and one foot.
These conventional bioelectrical impedance measuring apparatuses measure bioelectrical impedance by applying two pairs of electrodes to two selected body parts, such as both hands, both feet, or one hand and one foot, and therefore, there must be joints appearing in the current-flowing passage from one body part (or one electrode) to the other body part (or the other electrode), which was found by the inventor to be one major cause for incorrect measurement; during measurement the body sections may be bent or twisted at their joints, thus the object under measurement remains not stationary.
The total distance (for example, two arm lengths plus the trunk width) from one selected body part (one hand) to the other (the other hand) varies significantly with individuals, and therefore, accurate measurements can be hardly expected.
The handling of elongated cables and applying electrodes to selected body parts is inconvenient to use.
One object of the present invention is to provide an improved bioelectrical impedance measuring apparatus which is easy to use, and which is guaranteed to be free of incorrect measurement caused by some joints appearing in the current flowing passage intervening between two selected body parts and by the indefinite length between two selected body parts.
To attain this object the place of the body under measurement is limited to a selected joint-to-joint body portion (or joint-free body portion) such as the forearm extending from the wrist to the elbow or the portion extending from the ankle to the knee. Such a selected joint-to-joint body portion is called xe2x80x9cone body regionxe2x80x9d in the specification and claims.
Specifically a bioelectrical impedance measuring apparatus according to a first aspect of the present invention comprises a housing having a contact surface to be applied to one selected body region, the housing having an alternating current supplying device, a voltage measuring device and an arithmetic unit equipped therewith; a first pair of current electrodes so placed on the contact surface that the one selected body region may be put in contact with the current electrodes; and a first pair of voltage electrodes so placed on the contact surface between the pair of current electrodes that the one selected body region may be put in contact with the voltage electrodes; the alternating current supplying device supplying the first pair of current electrodes with alternating current; the voltage measuring device measuring the voltage appearing between the pair of voltage electrodes; and the arithmetic unit calculating the bioelectrical impedance from the supplying alternating current and the measured voltage.
The housing may include a rest whose upper surface defines the contact surface to be applied to the one selected body region, the contact surface being like a semi-cylindrical trough, and the current and voltage electrodes being so curved that they may be almost coplanar with the semi-cylindrical contact surface.
The bioelectrical impedance measuring apparatus may further comprises a cover member capable of pushing the one selected body region against the two pairs of electrodes.
A second pair of current electrodes and a second pair of voltage electrodes may be placed on the surface of the cover member which surface confronts the contact surface of the rest, the second electrodes being arranged in the same order and at same intervals as the counter first electrodes, thus sandwiching the one selected body region therebetween; and the alternating current supplying device may supply one and same alternating current to the first and second pairs of current electrodes simultaneously, making the two sets of confronting current electrodes function as a single composite pair of current electrodes; and the voltage measuring device may measure the voltage appearing between the first and second pairs of voltage electrodes, making the two sets of confronting voltage electrodes function as a single composite pair of voltage electrodes.
The bioelectrical impedance measuring apparatus may further comprise a positioning member which permits the one selected body region to be put in correct position, the positioning member being capable of effecting so positional adjustment as to fit on the one selected body region.
The one selected body region may be the right or left forearm, and the positioning member is a hand grip and/or an elbow rest.
The housing may include a rest whose upper surface defines the contact surface to be applied to the one selected body region, and a cover member pivotally fixed to one longitudinal edge of the rest, thereby permitting the one selected body region to be sandwiched between the rest and the cover member which is put in its closed position; and the first pairs of current and voltage electrodes may be placed on the surface of the cover member instead of the contact surface to push the two pairs of electrodes against the one selected body region lying on the contact surface of the rest.
The bioelectrical impedance measuring apparatus may further comprise a positioning member which permits the one selected body region to be put in correct position, the positioning member being capable of effecting so positional adjustment as to fit on the one selected body region.
The one selected body region may be the right or left forearm, and the positioning member is a hand grip and/or an elbow rest.
The one selected body region may be the right or left forearm.
The one selected body region may be the part of the right or left leg below the knee and above the ankle.
The bioelectrical impedance measuring apparatus may further comprise a display placed on a selected place of the housing other than the contact surface.
The housing may be so shaped and sized that a user can hold it in one hand while applying the contact surface to the one selected body region, still permitting the display to remain in sight.
The housing may have indentations formed on its opposite sides, on which indentations the fingers are placed, thereby facilitating the holding of the housing in one hand.
The display may be so arranged that the vertical direction of the display is orthogonally traverse to the direction in which the first pairs of current and voltage electrodes are aligned side by side, thereby facilitating the seeing of the information appearing in its screen.
The housing may have a display placed at a selected place other than the contact surface and a grip portion; and a recess may be so formed between the first pair of voltage electrodes that the contact surface space is reduced.
The housing may be so shaped and sized that a user can hold it with one hand while applying the contact surface to the one selected body region, still permitting the display to remain in sight.
The grip portion may be so formed to surround the recess, thereby facilitating the holding of the housing in one hand.
The display may be so arranged that the vertical direction of the display is orthogonally traverse to the direction in which the first pairs of current and voltage electrodes are aligned side by side, thereby facilitating the seeing of the information appearing in its screen.
The arithmetic unit may further calculate at least one of body fat, body water, pulse, or blood pressure.
The alternating current supplying device may supply a plurality of alternating currents of different frequencies; the voltage measuring device may measure the voltage every time when an alternating current of selected frequency is supplied; and the arithmetic unit may calculate the bioelectrical impedance values from each alternating current and corresponding voltage.
The alternating current supplying device may supply an alternating current of a single frequency; the voltage measuring device may further measure the phase of the voltage measured by it; and the arithmetic unit may further calculate the phase difference between the phase of the supplying alternating current and the phase of the measured voltage.
The arithmetic unit may further calculate at least one of the ratio between extra-cellular water and intra-cellular water, the ratio of body water and extra-cellular water, intra-cellular water, extra-cellular water, body water, or body fat.
A bioelectrical impedance measuring apparatus according to a second aspect of the present invention comprises a rest on which one selected body region may be put; a pair of current electrodes so placed on the rest that the one selected body region may be put in contact with the current electrodes; a pair of voltage electrodes so placed on the contact surface between the pair of current electrodes that the one selected body region may be put in contact with the voltage electrodes; a position member which permits the one selected body region to be put in correct position; an alternating current supplying device which supplies the pair of current electrodes with alternating current; a voltage measuring device which measures the voltage appearing between the pair of voltage electrodes; and an arithmetic unit which calculates the bioelectrical impedance from the supplying alternating current and the measured voltage.
A bioelectrical impedance measuring apparatus according to a third aspect of the present invention comprises a rest on which one selected body region may be put; a pair of current electrodes so placed on the rest that the one selected body region may be put in contact with the current electrodes; a pair of voltage electrodes so placed on the contact surface between the pair of current electrodes that the one selected body region may be put in contact with the voltage electrodes; a cover member capable of pushing the one selected body region against the two pairs of electrodes; an alternating current supplying device which supplies the pair of current electrodes with alternating current; a voltage measuring device which measures the voltage appearing between the pair of voltage electrodes; and an arithmetic unit which calculates the bioelectrical impedance from the supplying alternating current and the measured voltage.
A bioelectrical impedance measuring apparatus according to a fourth aspect of the present invention comprises a rest on which one selected body region may be put; a cover member so pivotally fixed to one longitudinal edge of the rest that the one selected body region may be sandwiched between the rest and the cover member which is put in its closed position; a pair of current electrodes and a pair of voltage electrodes so placed on the surface of the cover member to push the two pairs of electrodes against the one selected body region lying on the contact surface of the rest, the pair of voltage electrodes intervening between the pair of current electrodes; an alternating current supplying device which supplies the pair of current electrodes with alternating current; a voltage measuring device which measures the voltage appearing between the pair of voltage electrodes; and an arithmetic unit which calculates the bioelectrical impedance from the supplying alternating current and the measured voltage.
A bioelectrical impedance measuring apparatus according to a fifth aspect of the present invention comprises a housing having a contact surface to be applied to one selected body region and a grip portion, the housing having an alternating current supplying device, a voltage measuring device and an arithmetic unit equipped therewith; a pair of current electrodes so placed on the contact surface that the one selected body region may be put in contact with the current electrodes; a pair of voltage electrodes so placed on the contact surface between the pair of current electrodes that the selected one body region may be put in contact with the voltage electrodes; and a display placed on a selected place of the housing other than the contact surface; the alternating current supplying device supplying the first pair of current electrodes with alternating current; the voltage measuring device measuring the voltage appearing between the pair of voltage electrodes; the arithmetic unit calculating the bioelectrical impedance from the supplying alternating current and the measured voltage; and a recess being so formed between the first pair of voltage electrodes that the contact surface space is reduced.